Bioactivity of the Cymbopogon citratus (Poaceae) essential oil and its terpenoid constituents on the predatory bug, Podisus nigrispinus (Heteroptera: Pentatomidae)

Bruno Pandelo Brügger,Amélia Guimarães Carvalho,Barbara Monteiro De Castro E Castro,Carlos Frederico Wilcken,José Cola Zanuncio,Marcus Alvarenga Soares,Angelica Plata-Rueda,José Eduardo Serrão,Luis Carlos Martínez

doi:10.1038/s41598-019-44709-y

Abstract

Podisus nigrispinus Dallas (Heteroptera: Pentatomidae), released in biological control programs, is a predator of Lepidopteran and Coleopteran species. Lemongrass essential oil and its constituents can be toxic to this natural enemy. The major constituents of lemongrass essential oil are neral (31.5%), citral (26.1%), and geranyl acetate (2.27%). Six concentrations of lemongrass essential oil and of its citral and geranyl acetate constituents were applied to the thorax of P. nigrispinus nymphs and adults. The walking and respiratory behavior of the P. nigrispinus third-instar nymphs, treated with citral and geranyl acetate at the LD50 and LD90 doses, were analyzed with video and respirometer. The lemongrass essential oil toxicity increased from first- to fifth-instar P. nigrispinus nymphs. The P. nigrispinus respiration rates (μL de CO2 h−1/insect) with citral and geranyl acetate in the LD50 and LD90 differed. Nymphs exposed to the lemongrass essential oil and its constituents on treated surfaces presented irritability or were repelled. Podisus nigrispinus adults were tolerant to the lemongrass essential oil and its constituents, geranyl acetate and citral. The altered respiratory activity with geranyl acetate and the fact that they were irritated and repelled by citral suggest caution with regard to the use of the lemongrass essential oil and its constituents in integrated pest management incorporating this predator, in order to avoid diminishing its efficiency against the pests.

Highlights

Podisus nigrispinus Dallas (Heteroptera: Pentatomidae), released in biological control programs, is a predator of Lepidopteran and Coleopteran species
Effective use of P. nigrispinus in integrated pest management (IPM) programs depends on the compatibility of the predator with the other control methods being employed[21]
The increase in the lethal doses (LD50 and LD90) of the lemongrass essential oil from first to fifth instars of P. nigrispinus suggests that this predator progressively developed a tolerance as it matured

Summary

Introduction

Podisus nigrispinus Dallas (Heteroptera: Pentatomidae), released in biological control programs, is a predator of Lepidopteran and Coleopteran species. The biology and ecology of P. nigrispinus, including its development, morphology[6], predator-prey interaction[4], and feeding strategies such as extraoral digestion[1] have been studied This insect is reared in the laboratory and released in biological control programs in cotton[7], soybean[4], and tomato[8] crops. Terpenoids are products of secondary metabolism and are found in glandular hairs or secretory cavities of the plant cell wall in bark, flowers, fruits, leaves, roots and stems[25] Essential oils and their constituents cause lethal and sublethal effects on insects, such as biocide activity, infertility, irritability, phagoinhibition and repellency[23,26,27]. Essential plant oils can control pests[22,23,26,27]

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